Piston means for gas-operated firearms



Feb. 15, 1944. D, M, W|| 1AM$ 2,341,680

PIsToN-MEANS FOR GAS-OPERATED FIREARMS Filed Nov. 28, 1941 2 Sheets-Sheet 1 afwfmw Feb. l5, 1944. D. M. WILLIAMS PISTON-MEANS FOR GAS-OPERATED FIREARMS 2 Sheets-Sheet 2 Filed Nov. 28,` 1941 Patented Feb. 15, 1944 UNTTED STAT PISTON MEANS FOR GS-OPE'RATED FIREARMS f Application November 28, 1941, Serial No. 420,751

3 Claims.

The present invention relates to improvements in gas-operated self-loading rearms and more particularly to improvements in piston-means for gas-operated firearms of the type wherein the stroke of the piston under the urge of gases from the bore of the firearm, is but a minute fraction kof the stroke of thebreech-bolt or its equivalent which the piston serves to actuate. More particularly, the present invention relates to improvements in piston-means of the general type shown in my co-pending application, Serial No. 362,943, led October 2S, 1940.

In gas-operated self-loading firearms, the problem of avoiding the fouling of the parts by the residues from burnt powder, is a factor which must be provided for if a firearm is to be produced which will continue to function over long periods of usewith a minimum of attention and cleaning. Military firearms, in particular, should be able to continue to perform despite the most adverse conditions of use.

One of the objects of the present invention is to provide superior piston-means for gas-operated self-loading firearms which will continue to function effectively over long periods of use and with a minimum of attention, and which may be produced at a low cost for manufacture.

Another object of the present invention is to provide a gas-operated self-loading firearmstructure with superior `piston-means whereby the deleterious effects of residues from powdered gases are minimized without materially affecting the efficiency of the piston-means.

A further object of the present invention is to provide superior piston-means for firearms of the type referred to, and which piston-means embodies means for limiting the stroke of thepiston proper, and in which the said limiting-means also functions to minimize the deleterious effects of the residues of powder gases,` etc.

Still another object of the present invention is to provide superior piston-means of the general character above referred to, and which includes a removable stop-member for limiting the stroke tain modes of carrying out the present invention are 'shown for illustrative purposes:

Fig. `1` is ar broken View in side elevation of a firearm-barrel equipped with the improved piston-means of the present invention, the piston proper being shown in its normal forward position;

Fig. 2 is a broken view partly in side elevation and partly in vertical central-longitudinal section ofthe barrel and piston-means and with the piston proper shown in its normal position;

Fig. 3 is a longitudinal sectional View taken on the line 3-3 of Fig. 4, but showing the piston in its advanced position;

Fig. 4 is a transverse sectional View taken on the line #-4 of Fig. 2;

Fig. 5 is a broken underside view of the structure of the preceding figures;

Fig. 6 is a view in side elevation of the tubular stop-mem'ber detached;

Fig. rIis a view of the stop-member looking toward the rear or outer face thereof;

Fig. 8 is a View of the tubular stop-member looking toward the inner or forward face thereof;

`Fig. 9 is a central-longitudinal sectional view taken on the line 9 9 of Fig. 7; and

Fig. 101s a perspective view of the tubular stopmember.

The firearm-structure herein chosen for purposes of illustrating the present invention in'- cludes a barrel I5 suitable for use as a component of a gas-operated self-loading firearm and having an axial bore I6 extending therethrough'for the passage of bullets in the usual manner of firearms. Intermediate its respective opposite ends and preferably nearer the breech-end than the muzzle-end,the barrel I5 is provided with a depending cylinder-'lugl i1 which is preferably formed integral with the said barrel. The said cylinder-lug il is formed with a rearwardlyopening piston-chamber I t having a relativelyheavy front Wall I9. y y

Leading forwardly andfupwardly from the forward portion of the piston-chamber I8 in the cylinder-lug I l, is an inclined gas-passage 20 which communicates at its upper end with the bore it ofthe barrel i5 and intersects the rear face of the front wall I9 of the cylinder-lug Il at a point slightly below the upper end thereof. The said gas-passage 20 is in line with a not/chlike passage or recess 2i formed in the lower rear edge of the cylinder-lug il and through which a drill may be passed in an upwardly-andforwardly-inclined direction to produce the said gas-passage 20. The said 'passage 2i also serves as a locking-recess in a manner as will more fully hereinafter appear.

The forward portion of the piston-chamber I8 in the cylinder-lug I1 is of smooth cylindrical form while the rear portion thereof is slightly enlarged in diameter and is provided with internal threads 22. As a result of the difference in diameters of the respective front and rear portions of the piston-chamber I8, a rearwardlyfacing annular sealing-shoulder 23 results. Normally seated against the sealing-shoulder 23 is the forward face of a slender annular sealing-lip f 24 formed at the forward end of a ring-like or tubular stop-member generally designated by the reference character 25. The said tubular stopmember is provided with external threads 26 which intert with the threads 22 within the rear portion of the piston-chamber I 8 in the cylinder-lug I1, as is especially well shown in Figs. 2 and 3.

The tubular stop-member above referred to is provided with an axial passage 21 extending therethrough from front to rear and outwardly flared at its forward end to form a forwardlyfacing conically-contoured sealing-seat 28. At its rear end, the tubular stop-member 25 is formed with an annular outwardly-extending ange 29 formed with an annular series of eight (more or less) equidistant notches or recesses 30. The notches 38 just referred to open outwardly through the outer periphery of the flange 29 and intersect both the front and rear faces of the said flange.

In its axial passage 21, the stop-member 25 is formed with four (more or less) rib-like lands 3l extending longitudinally of the stop-member 25 and spaced from each other by an equal number of shallow longitudinal grooves 32. As shown,v both the lands 3| and the grooves 32 extend rearwardly and outwardly from the sealing-seat 28 of the stop-member 25 through to the rear face of the said stop-member.

The respective inner faces of the lands 3| within the axial passage 21 of the stop-member 25 are cylindrically-contoured to substantially conform to and guide the cylindrically-contoured stem 33 of a piston generally designated by the reference character 34. In addition to its relatively-slender stem 33, the piston 34 includes a cylindrically-contoured head 35 reciprocating in the smooth forward portion of the piston-chamber I8 in the cylinder-lug I1. In the particular structure shown, the stem 33 of the piston 34 projects rigidly rearwardlyffrom the head 35 to a point preferably normally beyond the rear face of the tubular stop-member 25. At the junction of the stem with the head 35, thel piston 34 is formed with a rearwardly-facing conically-contoured annular sealing-surface 36 which is adapted to engage with the similarly-contoured but forwardly-facing sealing-seat 28 at the forward end cf the tubular stop-member 25.

In its forward lower portion, the cylinder-lug I1 is formed with a vertical internally-threaded bore 31 opening through the under face of the said cylinder-lug and receiving an externallythreaded stem 38. The stem 38 just referred to forms a rigid feature of the rear end of a exible locking-member 39 extending longitudinally adjacent the under face of the cylinder-lug I1 substantially throughout the entire length thereof and a slight distance beyond the rear face of the said cylinder-lug. At its rear end, the flexible locking-member 39 is formed with a locking-head 40 dimensioned to simultaneously t in the notch-like recess 2I in the cylinder-lug I1 and into the adjacent one of the notches 38 in the flange 29 of the tubular stop-member 25. The flexible locking-member 39 is preferably formed of spring-tempered steel and is provided in the rear face of its locking-head 40 with a notch 4I adapted to receive the ange-like head 42 of a cartridge 43 shown by broken lines in Fig. 2.

Normally, the piston 34 is at the limit of its forward movement, as shown particularly well in Fig. 2, in which the forward face of its head 35 is in engagement with the rear face of the front wall I9 of the cylinder-lug I1. The piston 34 may actuate a wide variety of mechanisms such, for instance, as the action-slide 44 represented by broken linesin Fig. 1 and which per se forms no essential feature of the present invention. The action-slide 44 or its equivalent is normally `yieldingly pressed forwardly by a helical spring 45 or its equivalent. A mechanism suitable for actuation by the piston 34 and the associated elements of the present invention is disclosed in my co-pending application above referred to.

Operation Let it be assumed for purposes of description that the rearm is loaded. The discharge of the firearm willcause a bullet to be forced forwardly through the bore I6 of the barrel I5 with the result that gas pressure will pass downwardly and rearwardly in an inclined path from the said bore I6 through the inclined gas-passage 20. The gas under pressure passing through the gaspassage 20 will impinge upon the forward face of the head 35 of the piston 34. The said piston 34 will be forced sharply rearwardly by the gas pressure until its annular sealing-surface 36 engages with the annular sealing-seat 28 of the tubular stop-member 25, whereupon the rearward movement of the piston will be checked, as shown in Fig. 3. By the engagement just referred to, not only will the rearward movement of the piston 34 be checked after a relatively-short movement but the appreciable escape of gases rearwardly from the piston-chamber I8 will be prevented, so that the gas pressure within the bore I6 of the barrel I5 may be prevented from falling to a harmful extent before the bullet has been fully energized.

'Ihe very rapid though relatively-short rearward movement of the piston 34 as above described, will impart to the action-slide 44 or other desired feature of the rearm, a similar rearward movement which will continue after the said piston has ceased its rearward movement. When the energy developed by the discharge of the firearm and the action above referred to has dissipated itself, the action-slide 44 will return to its forward position under the urge of the spring 45 and will again restore the piston to the position in which it is shown in Fig. 2, preparatory to another discharge of the firearm.

Despite a. close sliding fit between the head 35 of the piston 34 'and the piston-chamber' I8, a measurable amount of gas under pressure will pass by the said head 35 and over long periods of use and in the absence of provision for their dissipation, residues would collect in measurable amounts upon the sealing-surface 36 and in thev axial passage 21 of the tubular stop-member 25.

As the piston 34 is driven rearwardly by gas pressure as above described, accumulated residues and condensates will be blown rearwardly throughthe shallow grooves 32 inthe tubular stop-member 25 and outwardly beyond the said stopmember.

The dsmountzng of the tubular stop-member Should it be desired for any reason to remove the tubular stop-member 25 from the cylinderlug l1, the flange-like head 42 (or other suitable tool) of a cartridge such as 43 (Fig. 2) may be inserted into the notch 4! 'in the rear face of the flexible locking-member 38. A downward draft upon the tool such as the cartridge 43 will iiex the locking-member 39 downwardly and remove its locking-head 40 from both the notch-like recess or passage 2| in the cylinder-lug l1 and the particular notch 3U in the stop-member 25 in which it has been located. The locking-member 39 may now be swung to one side about its stein 38 as a center into a clearance position as indicated by broken lines in Fig. 5. When the ilexible locking-member 39 is swung into a clearance position as just above described, the tubular stop-member 25 may be unthreaded from the piston-chamber i8 of the cylinder-lug I1 by means of a suitable tool engaging with one or more of the notches 3i! in the flange 29 of the said stop-member.

The tubular stop-member may be reinstalled in the cylinder-lug I1 by reversing the steps above referred to, and when the locking-member 39 is restored to the position in which it is shown by full lines particularly Well in Figs. 2, 4 and 5, the locking-head 40 of the said locking-member will serve to anchor the said stop-member against turning movement relative to the cylinder-lug l1, to thus guard against the accidental loosening eiects of repeated and violent discharges of the firearm.

The invention may be carried out in other specic ways that those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming Within the meaning and equivalency range of the appended claims are intended to be embraced therein.

I claim:

1. A :rearm-structure including in combination: a barrel having an axial bore therethrough; a cylinder located adjacent the said barrel and provided with a piston-chamber and with a gaspassage connecting the said piston-chamber with the bore of the said barrel, the said cylinder being also provided with a locking-recess; a piston reciprocating in the piston-chamber of the said cylinder and including a relatively-large-diametered head and a relatively-slender stem rigidly projecting from the said head; a ring-like niember having an axial passage therethrough receiving the stem of the said piston with capacity for the reciprccation of the said stem therein, the said ring-like member being threadedly connected to the said cylinder and provided with an annular series of locking-recesses; and a retirable locking-member simultaneously fitting in the locking-recess in the said cylinder and one of the locking-recesses of the said ring-like member to hold the latter against turning movement relative to the said cylinder.

2. A firearm-structure including in combination: a barrel having an axial bore therethrough; a cylinder located adjacent the said barrel and provided with a piston-chamber extending in substantial parallelism with the bore of the said barrel, the said cylinder being also provided with an inclined gas-passage leading upwardly from the said piston-chamber to the bore of the said barrel, the said cylinder also being provided with a drill-passage in a portion remote from the said barrel and aligned with the said gas-passage to permit the formation thereof by a drill passing through the said drill-passage; a piston reciprocating in the piston-chamber of the said cylinder and including a relatiVely-large-diametered head and a relativelyslender stem rigidly projecting from the said head; a ring-like member having an axial passage therethrough receiving the stem of the said piston, the said ring-like member being threadedly connected to the said cylinder and provided with an annular series of locking-recesses; and a retirable locking-member simultaneously fitting in the drill-passage in the said cylinder and in one of the locking-recesses of the said ring-like member to hold the latter against turning movement relative to the said cylinder.

3. A firearm-structure including in combination: a barrel having an axial bore therethrough; a cylinder adjacent to and rigid with the said barrel and provided with a piston-chamber closed at one end by an integral portion of the said cylinder and open at its opposite end, the

said cylinder being provided with an inclined gas-passage leading upwardly from the portion of the piston-chamber in the said lug adjacent the closed end of the piston-chamber and communicating with the bore of the said barrel, the said cylinder being formed adjacent its open end and at a point remote from the said barrel with a drill-passage aligned with the gas-passage of the cylinder to permit a drill to be passed through the said drill-passage to form the said gas-passage; a piston reciprocating in the piston-chamber of the said cylinder and including a head and a relatively-slender stem rigidly projecting from the said head; a ring-like member threaded into the open end of the piston-chamber in the said cylinder and formed with a radially-extending flange having an annular series of outwardlyopening locking-recesses therein; and a exible locking-member pivoted to the said cylinder and having a locking-head simultaneously fitting into the drill-passage of the said cylinder and into one of the locking-recesses in the iiange of the said ring-like member to hold the latter against turning movement relative to the said cylinder. DAVID M. WILLIAMS. 

